Regenerative procedures in aesthetic medicine

Excerpt from the book: Regenerative procedures in aesthetic medicine

Beauty and Aging

Eva Guisantes

Introduction

Aging affects all tissues of the body. But it is precisely on the aging of facial tissues that most studies are focused, and it is on the rejuvenation of this area that most therapeutic and surgical procedures are aimed. The face does not age uniformly, but due to several dynamic components. The changes that occur involve a complex interaction of osteochondral structures, skin, subcutaneous soft tissue, suspensory tendons, and septa. For proper correction, all these factors must be taken into account.

Facial aging is a multifactorial process. Endogenous aging represents histological and physiological changes resulting from apoptosis and other genetically determined processes. Exogenous aging is caused by prolonged exposure to aggressive external factors (smoking, alcohol, ultraviolet radiation (UV radiation), dehydration, poor nutrition, too high or too low temperatures, trauma, chemotherapy, radiation therapy). Clinical signs of aging in the facial area are associated with changes in all its structures (skin, subcutaneous fat, muscle and bone tissue).

The key to optimal rejuvenation results is appropriate analysis based on knowledge of anatomy and an understanding of its clinical significance.

Leather

The skin is subject to age-related changes (thinning of the epidermis, loss of collagen, elastosis), leading to the appearance of fine wrinkles and age spots, and dryness. Aging causes fragmentation of the collagen matrix of the dermis. The term “solar elastosis” is used to describe the histological appearance of the extracellular matrix of the dermis that has undergone photoaging. Solar elastosis is characterized by the accumulation of amorphous, pathologically altered elastin, surrounded by a smaller volume of disordered wavy collagen fibers. The loss of this extracellular collagen causes a loss of structural integrity of the matrix and a decrease in mechanical tension. There is an inability of fibroblasts to organize and produce new collagen. Thus, stimulation of neocollagenesis may improve the appearance of aging skin. The skin's ability to adapt to age-related loss of underlying soft tissue volume is influenced by both extrinsic and intrinsic factors.

Exposure to ultraviolet radiation (UVB) spectrum A and spectrum B leads to direct and indirect skin damage. UVB radiation is almost completely absorbed by the epidermis and therefore only UVB radiation causes photodamage. UVA radiation directly induces DNA alteration and indirectly causes cellular damage by generating free radicals, leading to increased oxidative stress and degradation surrounding collagen. The dermis undergoing photoaging exhibits histological features of chronic inflammation. When damaged by solar radiation, the epidermis undergoes characteristic histological changes, leading to an increase in its thickness, a slowdown in keratinocyte turnover and a decrease in the number of melanocytes. But, in addition, there are areas of increased concentration of melanocytes with increased production of melanin and its concentration in keratinocytes, manifested by age spots (solar lentigo) 1, 2].

Wrinkles are not formed randomly. Perhaps the main anatomical structures that determine their location and localization are the lymphatic vessels. Repeated contraction of the skin over a stable structure (vessel, nerve) can lead to changes in surface configuration (3).

Agents that stimulate collagen production include laser radiation, retinoic acid (superficial), deep chemical peeling, collagen, calcium hydroxyapatite. Stimulation of collagen production can be due to the formation of fibroblasts directly (fibroplasia) or indirectly (increase in the extracellular matrix, stretching effect). All of these methods replace collagen and slow down its loss (4). For solar lentigo, laser procedures, superficial application of retinoic acid and peeling have a certain effect. Injections of stabilized hyaluronic acid improve skin hydration.

Adipose tissue

Facial adipose tissue is divided by septa into superficial and deep packets relative to the superficial musculofascial system (SMAS) or facial muscles, forming different units [5]. This separation ensures that the facial muscles slide between the packages when moving. Vessels and nerves pass through the partitions that form the transition zones between fat packets. Many tendons that hold the soft tissues of the face come from the partitions between the bags [b]. In addition, with age, fat packets undergo consistent changes. On a young face the transition between them is imperceptible. As we age, the transition becomes more pronounced, with furrows forming.

The fat layer of the face is divided into superficial and deep.

Superficial fat packets

Nasolabial fat pad: the most medial fat pad of the cheek, least susceptible to age-related changes.

Superficial buccal fat pads:

- internal buccal fat pad: located lateral to the nasolabial fat pad;

- medial buccal fat packet: located superficially, in front of the parotid gland, between the medial and lateral superficial packets of the cheek;

- lateral buccal fat pad: the most lateral fat pad of the cheek - from the temple to the neck.

Forehead packets: There are three packets located in the forehead area.

The central frontal fat packet is located in the central part of the forehead, limited below by the nasal septum.

The internal frontal fat pads (left and right) are located between the central frontal fat pad and the lateral buccal fat pads on both sides.

Orbital fat pads: distinguish between infraorbital, supraorbital and lateral orbital. The nasolabial, internal buccal and infraorbital fat pads are collectively called the malar fat pad.

Premental (whisker) fat packs: upper and lower premental (whisker) fat packs.

Deep fat packs

The deep medial buccal fat pad (DMC) consists of parts - medial and lateral (DLC). The medial part is located posterior to the nasolabial packet and is limited by the deep pyriform space (Ristow's space) posteriorly. This is one of the packages most susceptible to age-related changes.

The infraorbital fat pad (SOOF) is located posterior to the orbicularis oculi muscle and is divided into medial and lateral parts: medial SOOF from the medial limbus to the lateral canthus and lateral SOOF from the lateral canthus to the temporal fat pad. Inferiorly, the SOOF is limited by the tear groove.

The postorbital fat pad (ROOF) is located posterior to the orbicularis oculi muscle in the upper eyelid.

Intraorbital fat packets: from the lower eyelid - inner, middle and outer; from the side of the upper eyelid - inner and middle.

The buccal fat pad includes the deep buccal fat pad (Bishat's lump) and its superior extension from the deep perimaxillary space to the superficial, subcutaneous plane below the cheekbone.

Age-related changes in fat packets

Traditionally, aging in the facial area is explained using the gravitational theory. According to this theory, ligaments weaken and gravitational prolapse of soft tissues occurs, which leads to sagging facial skin [7]. In addition, it was believed that repetitive movements of the facial muscles also weaken the ligaments. Research into facial fat pads has led to significant additions to theories of aging. Currently, the most widely accepted theory of aging of facial soft tissues is the volumetric theory [5, 8–14]. According to this theory, changes in the relief of the face, especially its middle third, are caused not by gravitational ptosis, but by a relative decrease in the volume of fat packets. The volume of some packets decreases before the appearance of clinical signs of aging (Fig. H). These two theories are not mutually exclusive, and facial aging likely reflects complex morphological changes with elements of gravitational ptosis and a decrease in the volume of adipose tissue. Studies show relative hypertrophy of superficial fat pads (especially the lower part of the nasolabial pad) and pronounced atrophy of deep fat pads (especially DMC and buccal fat) with age [15, 16]. According to the volumetric theory, the decrease in some fat packets with age leads to loss of support and prolapse of the overlying superficial subcutaneous fat, creating the characteristic picture of ptosis. Associated with this is the so-called pseudoptosis: loss of volume in one area can lead to the formation of folds in the neighboring one [4]. Atrophy of the buccal fat pads results in a loss of youthful midface convexity (negative vector; Fig. 4). A negative vector is said to exist if the maximum protruding point of the zygomatic bone projection is located behind the tangent to the pupil. The reduction of the deep periorbital buccal packets contributes to the deformation of the tear trough and the formation of the nasozygomatic cavity. Atrophy of the temporal fat pad leads to retraction of the temporal region. Age-related atrophy practically does not affect the lower part of the nasolabial packet.

But fat bags suffer not only from a decrease in volume. The packages in the middle third of the lip descend, their volume shifts downward [1, 15] (Fig. 5). In youth, the face has a V shape, with a wide middle third and less voluminous lower third. As the bags descend, the middle third loses volume and the bottom third increases in volume, resulting in an inversion of the youthful facial shape (Figure 6). Against the background of a downward shift, the transition between fat packets becomes more pronounced. On a young face, the transitions are smooth and the packages are close to each other. On an aging face, the transitions are pronounced, which leads to the formation of grooves (tear trough, nasozygomatic cavity, etc.), and the distance between the packets increases.

According to observations, the adipocyte of the deep buccal packet is on average smaller in size than the adipocyte of the superficial buccal packet [17]. The reasons for these differences have not been studied, but, apparently, the mechanical specificity of the environment of these two layers of adipose tissue in the middle third of the face may influence the morphological features of these adipocytes. Superficial packets are adjacent to the facial muscles, and deep packets are in contact with the facial skeleton. Deep packs, constantly pressed against the facial bones, play a relatively inert role as filler, planes along which the masticatory muscles glide, and are thus more susceptible to atrophy. Superficial packets, on the contrary, are located closer to the facial muscles, which may be due to a more active metabolism [14]

Clinical significance of facial rejuvenation

Due to the importance that facial fat acquires, the idea of the task of local rejuvenation has changed - from lifting to the introduction of fillers. These changes allow for more natural rejuvenation compared to classic skin resurfacing and SMAS, which are based on gravity theory and sometimes result in an unnatural appearance. Knowledge of the anatomy of facial fat pads allows you to apply rejuvenation techniques more accurately and targetedly. In this way, we can selectively increase the volume of subsiding deep packets, which gives the face a more natural appearance than masking folds by superficial layering of randomly localized injections of fat or fillers into the painting area, which saves the amount of fillers used. We can successfully reduce the nasolabial fold and restore the anterior projection of the cheek with injections into the DMC and Ristow's space [10]. The sharp transition between the eyelid-buccal junction and the deformed tear trough can be smoothed with injections into the medial part of the SOOF and supraperiosteal DMC. By increasing the lateral portion of the DMC, the anterior projection of the cheek may also increase and the transition between the anterior and lateral portions of the cheek may be smoothed. Fillers can be injected into the area of the medial and lateral superficial packages to complete contour correction [18].

The downward displacement of fat pads and the collapse of the midface lead to an inversion of its V-shape. Therefore, the introduction of fillers into the lower third of the face (marionette lines, premaxillary folds) requires caution, because with an increase in the volume of the lower third, the inversion of the face shape increases and it is not possible to obtain a sufficient rejuvenating effect. Restoring the volume of the middle third of the face by introducing fillers or autologous adipose tissue is one of the best tactics for local rejuvenation. But when the tissues of the lower third of the face sag, it is preferable to use not only fillers, but also lifting techniques (threads, surgical correction).

Muscles

From a mechanical point of view, the adipose tissue surrounding the facial muscles provides an excellent sliding plane. Over time, repeated contractions of the facial muscles contribute to changes in the distribution of fat tissue, pushing the tissue of deep fat packets out from under the muscle plane, resulting in a loss of youthful roundness and increased muscle tone at rest. This dynamic muscle effect may explain the decrease in deep muscle packages relative to superficial ones. With age, facial muscles gradually straighten, changing their relief from broadly convex to straight-flat. The curved, convex contour becomes straight, as the tissue of the deep fat pads protrudes from under the muscles, and the superficial fat pads increase in size. The amplitude of movement also decreases with age, and the face acquires a more uniform expression [19, 20]. Contraction of facial muscles leads to the appearance of facial wrinkles (“crow’s feet”, vertical and horizontal wrinkles on the forehead). Constant contraction leads to constant wrinkling of the skin and the transformation of dynamic wrinkles into static ones. An age-related increase in muscle tone at rest explains the effectiveness of botulinum toxin in anti-aging procedures. In young people, the depressor muscles (procerus muscle, corrugator muscles, orbicularis oculi muscles) are usually weaker than the levator muscles (frontalis muscle), and in older people, the depressor muscles are stronger than the levator muscles.

Facial ligaments

Facial ligaments are composed of collagen, proteoglycans, glycosaminoglycans and water. Rough large ligaments do not undergo significant primary age-related changes. Ligamentous changes predominantly consist of division into retinacular thinning branches running from the SMAS through the subcutaneous fat to the dermis, which over time are more susceptible to weakening with repeated movements [18, 21, 22]. The most common involutive processes affect the zygomatic ligament, orbital retinaculum ligament and mandibular retinaculum ligament

Age-related changes in bone tissue affect the origin of the ligaments and their points of attachment to the skin, and other adjacent structures are transformed as the position and therefore the course of the ligaments change. The ligaments on which the fat packets are suspended (superficial or deep) become thinner and sag, which creates a picture of ptosis of the corresponding fat packet and contributes to the deformation of the tear trough, the appearance of lip bags and sagging of the lower part of the face (jowls).

Bone structures

Age-related changes affect not only the soft tissues of the face, but also the underlying bone structures. Remodeling of the bone tissue of the skull is an important factor in facial aging. The bony skeleton of the face serves as a framework for the overlying soft tissues, creating a foundation on which tissues are superimposed. Bone resorption occurs in some areas [9, 23–27]. The most significant age-related changes concern the resorption of bone tissue of the orbit, upper and lower jaws (Fig. 7). The size of the orbit increases, more precisely, the height of the superomedial and inferolateral edges. The glabellar and maxillary angles decrease with age, and the upper jaw shifts posteriorly and its projection decreases (Fig. 8). The deep pyriform space increases with the posterior displacement of the columella, lateral crura, and base of the wings. The anterior nasal spine also moves posteriorly, promoting retraction of the columella, drooping of the tip, and apparent elongation of the nose. With age, the height of the mandibular ramus and the height and length of the body of the mandible decrease, and the mandibular angle increases. These changes occur regardless of gender. Remodeling of the facial bones occurs regardless of the condition of the teeth, but with tooth loss, the rate of bone resorption in the upper and lower jaws increases.

With age-related remodeling of bone structures, the space and support of soft tissues, especially fat pads, decreases, leading to the formation of wrinkles that resemble an accordion. Changes in the facial skeleton affect not only the overall shape of the face, but also the position of the ligaments and septa. The expansion of the infraorbital margin leads to the advancement of the orbital septum and pseudoprolapse of intraorbital fat packets, as the holding capacity of the orbital septum decreases. The retaining ligament of the orbicularis muscle loses its horizontal position relative to the structures located below, leading to destabilization of the orbicularis oculi muscle and sagging of the ROOF and SOOF. Remodeling of the superolateral orbital rim promotes exposure of subcutaneous fat to the medial upper eyelid, which weakens the orbital septum. Changes in the superior part of the orbit lead to displacement of soft tissues into the orbit, causing brow ptosis and lateral tissue overhang. Bone resorption of the maxilla and pyriform space, ligament laxity, skin laxity, changes in muscle physiology, gravity destabilizes the subcutaneous fat pad above the nasolabial groove, and the fat tissue moves downward. The zygomaticus major and buccal muscles are firmly attached to the skin, forming the nasolabial groove and delimiting the nasolabial fat pad inferiorly along with the SMAS. Fatty tissue does not migrate deeply to the nasolabial fold below, but due to pressure from above, the bulging of fatty tissue above the groove becomes visible, leading to deepening and sagging of the nasolabial folds. With age-related reduction in the projection of the upper jaw, the deformation of the tear trough and the severity of the sacs increase. A decrease in the volume of the lower jaw contributes to sagging of the platysma and soft tissues of the neck, blurred jaw line, and the appearance of jowls (Fig. 9). Undeveloped facial skeleton

Rice. 9. Young (left) and old (right) face. (A) Horizontal wrinkles on the forehead due to contraction of the occipitofrontal muscle. (B) Glabellar wrinkles due to contraction of the procerus and corrugator muscles. (B) Wrinkles around the eye due to contraction of the orbicularis oculi muscle. Ptosis of the eyebrow and sagging ROOF due to laxity of the orbicularis oculi muscle and retinaculum tendon and bone resorption

fabrics. (D) Deformation of the tear trough, aggravated by bone resorption of the orbit and maxilla, laxity of the retinaculum orbital and zygomatic ligaments, and changes in SOOF. (E) The nasolabial groove is formed by the proper superficial nasolabial fat pad and the extension of the underlying facial muscles. Resorption of the maxilla and pyriform space structures contributes to sagging of the nasolabial folds. (E) Jaw deformity. The mandibular ligament attaches the skin to the bone, and the superficial and deep fat packets behind it are attached more loosely and can move downwards, forming jowls. Resorption of the bone tissue of the lower jaw leads to jowl deformation (hypoplasia of the midface, microgenia, posterior displacement of the supraorbital margin) and means a predisposition to premature age-related changes.

conclusions

To return a face to a youthful appearance, it is necessary to understand age-related morphological changes. Depending on the action of internal and external factors, these changes affect the facial skeleton, fat packets, and soft tissues to varying degrees. A balanced approach to facial rejuvenation, combining the build-up of bone structures and adipose tissue and the reposition of soft tissues, avoids the problems of insufficient correction of involutive changes. Bone resorption is corrected using calcium hydroxyapatite injections or implantation. The reduction in the volume of fat packets can be compensated by injecting fillers or transplanting fat tissue in the areas of collapse. Surgical techniques are used in the area of SMAS of the retaining ligaments and structures of the eyelid. Botulinum toxin is used for age-related increased muscle tone at rest. Skin rejuvenation is achieved using tretinoin, laser procedures, and peeling. To restore signs of youth, an individual, comprehensive approach is required.

Buy the book: Regenerative procedures in aesthetic medicine • Ed. E. Pinto, J. Fontdevili; Per. from English; Ed. NOT. Manturova